I was a research assistant at Karisoke Research Centre in 1974 and the author inteviewed me over the phone. I have said from the beginning that no one entered Dian's cabin by cutting the tin sheet metal and woven grass matting that lined all our cabins. The noise would have been considerable.
I also knew Rwelekana and though he was often treated badly by Fossey and camp staff I don't believe he had anything to do with Fossey's death. Dian was had no lack of enemies and had no qualms about creating them. All the author said is plausible and most who worked with Fossey could have predicted an untimely end.
Dian often told me the only way she was leaving Karisoke was in a wood box. She had the box correct but never had to leave Karisoke.
We often put the famous on pedastles and forget they are human and vulnerable like everyone else.